<?php
/**
 * Created by PhpStorm.
 * User: JYuans
 * Date: 2019/11/27
 * Time: 14:55
 */
$str = 100;
$str_len = strlen($str);
$str_flag = "";
for($i = 0;$i < $str_len;$i++){
    $str_flag = $str_flag."0";
}
echo $str_flag;